I'm no expert so anything I say is purely opinion...
I would say if you the opportunity get a signed release form for the location, but I haven't ever had to prove to someone that I was allowed to use a location. I haven't seen the film, but apparently for human centipede in a scene they wanted to film along a highway. They requested permission but were denied but decided to film their anyway, and this is on a professional set. I don't know if they got in trouble, but usually I think that locations are overlooked. Organizers care a lot more about music and your actors